Examinando por Autor "Kegler, Alexandra"
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- PublicaciónAcceso abiertoA theranostic PSMA ligand for PET imaging and retargeting of T cells expressing the universal chimeric antigen receptor UniCAR(Taylor & Francis Group, 2019-09-07) Arndt, Claudia; Feldmann, Anja; Koristka, Stefanie; Schäfer, Martin; Bergmann, Ralf; Mitwasi, Nicola; Berndt, Nicole; Bachmann, Dominik; Kegler, Alexandra; Schmitz, Marc; Puentes-Cala, Edinson; Soto, Javier-Andrés; Ehninger, Gerhard; Pietzsch, Jens; Liolios, Christos; Wunderlich, Gerd; Kotzerke, Jörg; Kopka, Klaus; Bachmann, Michael; Taylor & Francis GroupChimeric antigen receptor (CAR) T cells have shown impressive therapeutic potential. Due to the lack of direct control mechanisms, therapy-related adverse reactions including cytokine release- and tumor lysis syndrome can even become life-threatening. In case of target antigen expression on non-malignant cells, CAR T cells can also attack healthy tissues. To overcome such side effects, we have established a modular CAR platform termed UniCAR: UniCAR T cells per se are inert as they recognize a peptide epitope (UniCAR epitope) that is not accessible on the surface of living cells. Bifunctional adapter molecules termed target modules (TM) can cross-link UniCAR T cells with target cells. In the absence of TMs, UniCAR T cells automatically turn off. Until now, all UniCAR TMs were constructed by fusion of the UniCAR epitope to an antibody domain. To open up the wide field of low-molecular-weight compounds for retargeting of UniCAR T cells to tumor cells, and to follow in parallel the progress of UniCAR T cell therapy by PET imaging we challenged the idea to convert a PET tracer into a UniCAR-TM. For proof of concept, we selected the clinically used PET tracer PSMA-11, which binds to the prostate-specific membrane antigen overexpressed in prostate carcinoma. Here we show that fusion of the UniCAR epitope to PSMA-11 results in a low-molecular-weight theranostic compound that can be used for both retargeting of UniCAR T cells to tumor cells, and for non-invasive PET imaging and thus represents a member of a novel class of theranostics.
- PublicaciónAcceso abiertoAn oligo-His-tag of a targeting module does not influence its biodistribution and the retargeting capabilities of UniCAR T cells(2019-07-29) Jureczek, Justyna; Bergmann, Ralf; Berndt, Nicole; Koristka, Stefanie; Kegler, Alexandra; Puentes-Cala, Edinson; Soto, Javier-Andrés; Arndt, Claudia; Bachmann, Michael; Feldmann, AnjaRecently, we established the controllable modular UniCAR platform technology to advance the efficacy and safety of CAR T cell therapy. The UniCAR system is composed of (i) target modules (TMs) and (ii) UniCAR armed T cells. TMs are bispecific molecules that are able to bind to the tumor cell surface and simultaneously to UniCAR T cells. For interaction with UniCAR T cells, TMs contain a peptide epitope sequence which is recognised by UniCAR T cells. So far, a series of TMs against a variety of tumor targets including against the prostate stem cell antigen (PSCA) were constructed and functionally characterised. In order to facilitate their purification all these TMs are expressed as recombinant proteins equipped with an oligo-His-tag. The aim of the here presented manuscript was to learn whether or not the oligo-His-tag of the TM influences the UniCAR system. For this purpose, we constructed TMs against PSCA equipped with or lacking an oligo-His-tag. Both TMs were compared side by side including for functionality and biodistribution. According to our data, an oligo-His-tag of a UniCAR TM has only little if any effect on its binding affinity, in vitro and in vivo killing capability and in vivo biodistribution.
- PublicaciónAcceso abiertoAnd yet it moves: Oxidation of the nuclear autoantigen La/SS-B is the driving force for nucleo-cytoplasmic shuttling(International Journal of Molecular Sciences, 2021-09-08) Berndt, Nicole; Bippes, Claudia C.; Michalk, Irene; Bartsch, Tabea; Arndt, Claudia; Puentes-Cala, Edinson; Soto, Javier-Andres; Loureiro, Liliana R.; Kegler, Alexandra; Bachmann, Dominik; Gross, Joanne K.; Gross, Tim; Kurien, Biji T.; Hal Scofield, R.; Darise Farris, A.; James, Judith A.; Bergmann, Ralf; Schmitz, Marc; Feldmann, Anja; Bachmann, Michael P.; MasiraDecades ago, we and many other groups showed a nucleo-cytoplasmic translocation of La protein in cultured cells. This shuttling of La protein was seen after UV irradiation, virus infections, hydrogen peroxide exposure and the Fenton reaction based on iron or copper ions. All of these conditions are somehow related to oxidative stress. Unfortunately, these harsh conditions could also cause an artificial release of La protein. Even until today, the shuttling and the cytoplasmic function of La/SS-B is controversially discussed. Moreover, the driving mechanism for the shuttling of La protein remains unclear. Recently, we showed that La protein undergoes redox-dependent conformational changes. Moreover, we developed anti-La monoclonal antibodies (anti-La mAbs), which are specific for either the reduced form of La protein or the oxidized form. Using these tools, here we show that redox-dependent conformational changes are the driving force for the shuttling of La protein. Moreover, we show that translocation of La protein to the cytoplasm can be triggered in a ligand/receptor-dependent manner under physiological conditions. We show that ligands of toll-like receptors lead to a redox-dependent shuttling of La protein. The shuttling of La protein depends on the redox status of the respective cell type. Endothelial cells are usually resistant to the shuttling of La protein, while dendritic cells are highly sensitive. However, the deprivation of intracellular reducing agents in endothelial cells makes endothelial cells sensitive to a redox-dependent shuttling of La protein.